Nitride semiconductor substrate and method of manufacturing the same

Abstract

A nitride semiconductor substrate suitable for a normally-off type high breakdown-voltage device and a method of manufacturing the substrate are provided allowing both a higher threshold voltage and improvement in current collapse. In a nitride semiconductor substrate 10 having a substrate 1, a buffer layer 2 formed on one principal plane of the substrate 1, an intermediate layer 3 formed on the buffer layer 2, an electron transport layer 4 formed on the intermediate layer 3, and an electron supply layer 5 formed on the electron transport layer 4, the intermediate layer 3 has a thickness of 200 nm to 1500 nm and a carbon concentration of 5×1016 atoms/cm3 to 1×1018 atoms/cm3 and is of AlxGa1-xN (0.05≦x≦0.24), and the electron transport layer 4 has a thickness of 5 nm to 200 nm and is of AlyGa1-yN (0≦y≦0.04).

Dependencies are inferred from the claim text.